My approach to programming is that I should learn just
what exists and where to find it, be it documention, tools
or code. As a result, when the need arises, I will be able to
acquire the needed competence.

This is not strictly true so.
I think that if you choose perl, you need to know about regexps
and many idioms involving hash, for example.

About certification, I think the field is so large and so unstalbe that certification cannot cover it. It would lead to uniformity which is decidely not perlish. Choosing your tools is very much one of the most important step. So imposing them on the programmer is
a sure way toward ossification.